1. Field of the Invention
The present invention relates to an endoscope and a supportive member for bending operation of the endoscope, and more particularly to an endoscope in which a bending operation knob is provided and a supportive member for bending operation of the endoscope.
2. Description of the Related Art
Conventionally, endoscopes are widely utilized for observations and various kinds of treatments of examined regions inside body cavities and the like. The endoscope has an elongated insertion portion which can be inserted inside the body cavities.
The endoscope, which is provided with a flexible insertion portion, generally includes a bendable portion. The bendable portion is a distal end part of the insertion portion, and bending pieces are housed therein. A traction member such as a bending wire penetrates through the insertion portion of the endoscope. The bending wire is connected to the bending piece in the bendable portion. Further, a pair of bending operation knobs is provided in an operation portion connected to the proximal end of the insertion portion of the endoscope. An operator rotates the pair of bending operation knobs to pull and/or loosen the bending wire. According to the operation by the operator, the bendable portion of the endoscope bends in a desired direction, i.e., up, down, to the left, and to the right. There are two bending operation knobs in the operation portion, one for upward and downward bending and another for rightward and leftward bending. The operator selects and rotates one of the two bending operation knobs as appropriate to bend the bendable portion at a desired angle. Thus, the operator can easily observe the examined region by directing an observation optical system arranged at a distal end portion of the insertion portion toward a target direction. In addition, the operator can easily insert the insertion portion of the endoscope into the examined region.
For example, Japanese Patent Application Laid-Open No. 62-32932 describes an endoscope which has a pair of bending operation knobs provided in an operation portion for bending the insertion portion of the endoscope in upward and downward directions and rightward and leftward directions.
However, when the endoscope is employed in medical field, e.g., when the operator inserts the insertion portion of the endoscope into a large intestine, which is a body cavity of a patient, peristaltic movements of the large intestine sometimes works to push the insertion portion towards an anus side and out of the large intestine. Therefore, the operator has to push the insertion portion of the endoscope into the large intestine by holding the insertion portion by one hand while holding the operation portion of the endoscope by another hand. In addition, when the distal end portion of the endoscope reaches a curved portion, such as a sigmoid colon, in the large intestine, the operator needs to direct the distal end portion of the endoscope in a desired direction of insertion by bending the bendable portion of the endoscope in order to facilitate the farther insertion. For bending the bendable portion, the operator manipulates the bending operation knobs in the operation portion with the hand that holds the operation portion of the endoscope, thereby bending the bendable portion to direct the distal end portion of the endoscope in a direction along the curve of the large intestine, while pushing the insertion portion of the endoscope into the large intestine with the other hand.
Further, when the operator directs the distal end portion of the endoscope toward a desired direction for the observation of the examined region inside the body cavity of the patient after the distal end portion reaches the examined region, the operator is required to hold the insertion portion of the endoscope with the other hand in order to prevent the peristaltic movements of the large intestine, for example, from pushing back the insertion portion of the endoscope towards the anus side. Therefore, in some cases as described above, the operator needs to manipulate a pair of bending operation knobs by one hand in order to bend and direct the distal end portion of the endoscope upward, downward, rightward, and/or leftward.
The operator should to be highly skilled to direct the distal end portion of the endoscope toward a desired direction while manipulating the pair of bending operation knobs with one hand. Meanwhile, the size of the hand varies from one operator to another, and the number of female medical doctors, who are expected to have relatively small hands, increases. For medical doctors with small hands, it is not easy to adjust the direction of the bendable portion of the endoscope in four directions, in other words, it is not easy to manipulate two bending operation knobs simultaneously in order to bend the bendable portion in rightward/leftward or upward/downward.
In electronic endoscope systems, the upward/downward directions mentioned above correspond to upward/downward directions on a screen of a monitor, and a picture moves on the screen according to the bending operation. During the bending operation, the operator generally performs upward/downward bending operations more frequently than rightward/leftward bending operations by rotating the knobs and bending the bendable portion of the endoscope upward/downward on the screen of the monitor. Therefore, in general endoscopes, the upward/downward bending operation knob is generally arranged closer to the operation portion.